herd was used to investigate changes composition of goat during lactation and their effects on the sensory quality and yield of hard and semi-hard cheeses, Milk was analyzed for fat. protein, cascin, total kolida and Komatic cell count SCC) and cheese was assayed for of fist, protein and moisture, Sensory evaluation of the cheeses was performed to establish the relationship between yield, quality and sensory score. The chemical composition of gaat milk changed significantly over lactation, resulting in variation in yield and sensory quality of hard and semi-hard cheeses. While casein content of goat milk did not change significantly as lactation advanced, SCC increased from early to late lactation. There were significant differences in flavor, body and texture, and total sensary scoresofeither cheese type among aging times of 8, 16 and or 24 week, which indicates that the cheeses can be consumed after 8 week or similar sensory quality as with longer aging. In hard cheese, yield was highly conelated with milk fat, protein or total solids whereas only milk total solids content was highly correlated with semi-hard cheese yield. These findings indicate need to adjust cheese making procedures over the duration of lactation to incroase milk nutrient recoverics and thus increase chcese yield However, a year-round breeding system should mininize variation in chemical composition in bulk tank goat milk during lactation and help maintain consistent quality and yicld of cheeses throughout the year, D 2004 Elsevier V All rights reserved.